For instance, Dorri et al. [1]} presented a Blockchain-based mechanism for resolving the issue of access control for multiple interacting entities in an IoT-based decentralised smart home environment, such as the cloud, users, and IoT devices. Each home has its own private Blockchain in this scheme, where the multiple miners keep a policy header to control all home access requests. However, this mechanism mainly focused on distribution and recording access privileges on the immutable ledger in Blockchain. Further, Maesa et al. [2]} proposed a blockchain-based access control delegation mechanism for storing and transferring expressions about access rights to a given resource in the form of transactions. To secure the validation of access rights, Andersen et al. [3]} proposed a scalable decentralisation authorisation mechanism that grants access to users via advanced cryptographic features. In addition to access delegation, a reverse discoverable decryption protocol protects shared access privileges between administrative domains. Pinno et al. [4]} presented a distributed architecture built on Blockchain technology to govern access to IoT devices and ensure transparent authorisation. This architecture secures relationships between users and devices using different access control models, including ACL, CapBAC, and ABAC. Also, Ding et al. [5]} proposed an IoT access management system built on Blockchain that simplifies the process of authorising IoT devices based on their attributes. The immutability feature of Blockchain is used to store attribute distribution in the form of transactions for permission and revocation. While these access control solutions addressed the aforementioned issues effectively by maintaining access policies on a tamper-proof ledger, they vastly overstated the full potential of blockchain technology by utilising its advanced features for performing various computation functions.
